The Collagen Research Has a Numbers Problem (And We Fell For It Too)

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Today’s Health Upgrade

On Our Radar
Why Eating More (And Moving More) Could Help You Keep Weight Off

As we discussed yesterday, the hard part of weight loss isn't figuring out how to initially get the scale moving in the right direction. It's afterward, when you're told the smaller portions are forever. 

A tightly controlled lab study suggests moving more and eating more might leave you more satisfied with your meals and help you maintain your results. 

Researchers put healthy adults in a metabolic chamber, a sealed room that tracks every calorie you burn. Each person cycled through day-long stays at three activity levels, set by how long they walked on a treadmill. Food varied too, from reduced calories to no restrictions and eating until satisfied. 

On the low-activity days, GLP-1 (a hormone that helps you feel full, which many of you know from medications like Ozempic) dropped. Ghrelin, the hunger hormone, often climbed. People felt hungrier and wanted to eat more when they moved less.

On active days, appetite matched what they actually needed.

Researchers call this energy flux: the amount of energy (calories) that moves through you while what you eat and what you burn stay balanced.

Most people are familiar with energy balance: calories in, calories out. Energy flux is the amount of energy that moves through you. Someone who can consume 1,800 calories a day and stay in maintenance is lower flux than someone who can eat 2,600 and hold the same weight.

But what these researchers found is that humans aren’t great at finding balance intuitively.

Your body is good at asking for more food when you move more. It's bad at asking for less when you move less.

The idea is that human appetite was calibrated for bodies that moved much of the day. In that active range, the signals line up. Working muscles clear blood sugar more easily, so you need less insulin, and your gut releases more of the hormones that tell your brain you've had enough.

When you drop below a certain level of movement, those signals get fuzzy, so hunger stops tracking what you burn.

Researchers call that the "non-regulated zone." It's still a hypothesis, built mostly on short studies like this one, which are single days in a lab with healthy adults, not months of real life after a big weight loss.

Unfortunately, no long-term trial has tested flux directly. But we’ve seen it work in the app and the lab. And in the Pump Club lab, Ketchell has gradually increased his calories by nearly 1,000 per day without gaining a calorie by extending his early-morning walks. 

And the outcomes line up with people who keep large losses off for years, who tend to burn more through activity and so eat more.

The hard part is that some people eat back more than they burn, which is why food selection matters so much for most people. And it’s why the calorie tracker and Arnold Intelligence work so well for people in the Pump Club app: people say the system gently pushes them toward more filling, whole foods. 

Weight training matters, and muscle plays a key role in preventing weight regain. But a gym isn’t necessary. In the study above, the higher energy flux came from walking more. 

Add the movement first, and let a small increase in food follow. 

For context, the high-energy-flux participants walked for about 2 hours 45 minutes on the treadmill at 2.5 mph. That let them eat 2,850 calories per day compared to about 2,300. So for about every hour of walking, you can factor in roughly 150-200 extra calories.

If you want to know it’s working for you, give yourself two weeks at a higher step count and monitor the scale. If the scale goes up, you’re consuming more energy than you’ve added; if it goes down, you’re consuming less; if it stays roughly the same, you’ve hit maintenance at a higher energy flux.

Together With Celluma
Can Red Light Help With The Frustrations of Aging?

The strongest plan for aging well fits on a short list: lift weights, get enough sleep, eat plenty of protein and fiber, build most meals from whole foods, connect with friends and loved ones.

Beyond that, most longevity hacks are, well, just that — more hack than help.

But there’s a short list of newer technologies — including red light therapy — that research suggests could help with some of the bigger frustrations of aging. 

A large 2025 review of more than 200 randomized trials found encouraging evidence for thinning hair, achy knees, and wrinkles.

Hair loss produced one of the strongest and most consistent results. A separate meta-analysis of randomized trials found that red light increased hair density in adults with pattern hair loss, the most common form in men and women.

Scientists believe the light is absorbed by mitochondria, the parts of your cells that produce energy. This may help struggling follicles function better, improve blood flow to the scalp, and keep hairs in their growth phase longer.

Studies generally required months of regular use. Realistically, you may see thicker coverage from the hair you still have, not a full head of hair.

Red and near-infrared light may also help people with knee osteoarthritis move with less pain. An analysis of 22 placebo-controlled trials found improvements in pain and daily function, with the largest benefits appearing when researchers used specific, measured doses. Pain relief peaked several weeks after treatment ended.

Scientists believe it might reduce inflammation and change how pain signals are transmitted. Many of the studies also paired light therapy with exercise, which is an important distinction. Red light may make movement more comfortable; exercise remains one of the best arthritis treatments.

And the evidence for wrinkles is promising. In a trial focused exclusively on women ages 40 to 65, red light treatments reduced wrinkle volume around the eyes by about 30 percent.

Lab studies suggest that red light may prompt skin cells to produce more collagen, the protein that helps skin stay firm and smooth. Collagen production naturally declines with age.

Look closely at those studies, and you'll see a pattern. Each benefit came from its own wavelengths, dose, and schedule. Hair got one protocol. Knees got another. Skin got another.

That's where most at-home light therapy falls apart. People end up with a mask for their face, a wrap for their knee, a drawer full of chargers, and no real idea whether any of them delivers what the research actually tested.

When we tested red light devices for effectiveness and FDA clearance, the Celluma NOVA was the one that covered everything in this research.

It's a compact, flexible panel that conforms to your scalp, knee, lower back, or face. It runs on a battery, so you can use it on the couch or pack it in a carry-on. It uses blue, red, and near-infrared light, with a separate program for each job, and it's FDA-cleared for five different goals, including hair growth.

Compact is the tradeoff. If you want to treat a bigger area at once, like your whole back or both thighs, a larger panel makes more sense. That's why we like that Celluma makes 14 devices in different sizes and configurations, so you can match the device to what you actually want to treat.

As a Pump Club reader, you get up to $1,000 off with code PUMPED. It's HSA/FSA eligible, which may lower your cost further, and shipping is free on orders over $1,000.

The short list still comes first, and red light therapy is your insurance that makes a few frustrations easier to live with.

Not So Fast
Collagen Research Has a Numbers Problem

If we’ve said it once, we’ll say it 1,000 times: our job is to get it right, not be right. So if we make mistakes, or the research changes, we’ll be the first to own it. 

In February, we told you collagen can work to improve your skin health. That was based on two big reviews covering 26 trials.

But a new paper went back to the original trials and checked the math behind both reviews, and many of the numbers that made collagen look proven didn't match what the trials actually reported. Fundamentally, the numbers were wrong, and they were reported as fact.

Both reviews treated standard errors as standard deviations. That swaps a measure of how much results vary for a much smaller one, giving some studies far more weight than they earned and making the effect look bigger.

One trial's "hydration" data came from a survey question, with no actual skin measurement. Some trials had no placebo group. Subject counts were wrong. Methods were misdescribed, percentage changes were miscalculated, and some studies (or parts of their data) were left out entirely.

We read the meta-analysis but didn't cross-check all the data against the original studies. That’s on us. And when a separate group of researchers took the time to go back through every morsel of data, many of the claims started to fall apart. 

There were other holes too. Many studies didn't track whether people also changed their skincare, got procedures, or ate more protein. Some barely described the placebo, which matters because collagen has a taste that's hard to fake. Few defined how big a change would actually be noticeable. A bump on a skin-hydration meter after two months isn't the same as skin that looks younger, let alone stays that way.

Meta-analyses can be great, but they have a limitation: you usually don’t see all the original research. These things are supposed to be caught before journals publish studies, but mistakes happen.

So does collagen work for skin health? The honest answer is we don’t know. This paper does not prove collagen is useless for your skin. It shows the evidence we leaned on can't answer the question either way.

If you like your collagen, you think it’s doing something, and it fits your budget, then there’s likely no harm in keeping it. But based on the uncertainty, we wouldn’t recommend paying a premium. If better skin is your focus, sunscreen and a retinoid have the evidence collagen doesn't. 

The Pump Club Promise: Do you have a question you’re curious about? Read a headline that has you confused? Always had a question without a clear answer? Reply back to us, and let us know. We get hundreds of emails each day. We can’t reply to all of them, but we feature your questions every week in these newsletters. We write this for you, so if we can give you more clarity and control over your health, we want to help. That’s how you become better every day. 

Mindset
Purpose Doesn’t Have to Be Your Life’s Work

“Find your purpose” sounds like good advice until it starts to feel like an assignment. One perfect mission. One calling that explains your career, relationships, and place in the world. If you haven’t found it, it can feel like you’re falling behind.

However, psychological research offers a more forgiving and much more useful perspective.

Purpose helps make life feel meaningful. But it doesn’t need to be grand, permanent, or your only source of meaning.

Psychologists have identified three parts of a meaningful life:

1) Coherence is the sense that your life makes sense.
2) Purpose gives you goals and direction.
3) Mattering is the belief that your life has value.

Those pieces overlap, but they aren’t interchangeable. Researchers measured them separately and followed participants for a month. After accounting for the overlap, purpose didn’t independently predict whether people later judged their lives as meaningful. Mattering did most of that work.

Purpose still has value. The study simply challenges the pressure to identify one purpose that will make everything fall into place.

Like all studies, this research has limits, both in the participants' ages and in how meaning is measured. But the outcomes line up across many observational studies, suggesting there’s something to a multi-faceted approach to appreciating meaning. 

If you feel like you struggle with purpose, try shrinking the timeline and focusing on shorter-term goals connected to something (really, anything) you want to accomplish. 

Ask yourself: What deserves my effort for the next 12 weeks?

It could be a project, a person you want to support, or a goal that gives your days some direction. Write down the answer, then choose one action you can take this week.

That goal doesn’t have to last forever. It only has to give you somewhere worth going now.

The Positive Corner of The Internet
About Arnold’s Pump Club Editorial Standards

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Publisher: Arnold Schwarzenegger​

Editors-in-chief: Adam Bornstein and Daniel Ketchell